基于逐4 h尺度的粤西典型流域降雨径流污染特征分析

Pollutant characteristics of rainfall runoff in a typical basin in Western Guangdong based on a 4 h time step resolution

以面源为主要污染源的典型流域——广东粤西潭水河流域为研究对象,建立了逐4 h降雨事件划分方法,基于时间跨度超过1年的长时间序列的降雨和断面水质观测数据,分析了流域降雨与水质变化特征、不同降雨事件下水质指标变化规律,并采用SPSS相关分析方法,对降雨事件与各典型水质指标之间的相关性进行了分析。结果表明:潭水河流域降雨量在时间分布上极不均匀,流域水质对降雨强度表现出明显的敏感性。不同水质指标对降雨事件反应的差异特征显著,其中溶解氧浓度在所有降雨时段中都较晴天有所降低,暴雨时溶解氧降低幅度最大;浊度、电导率随降雨强度增大分别呈现出明显正增长和负增长的伴随关系,可见流域内降雨—径流事件的泥沙响应迅速且显著;高锰酸盐指数、氨氮、总磷、总氮等污染指标变化趋势基本一致,随着降雨强度增大,总体呈现先升高后降低的趋势,暴雨时升高幅度最大。溶解氧改善需特别关注暴雨过程耗氧污染物削减和治理,而针对高锰酸盐指数、氨氮、总磷、总氮等污染指标应推进汛期面源污染的协同治理和同步削减。考虑到不同降雨事件对不同污染指标的影响性质与程度不尽相同,可根据关键污染指标特征规律,结合天气预报开展汛期污染削峰的精细应对。

A typical basin with non-point sources as its main pollution source-Tanshui River Basin in Western Guangdong was selected as research object,and a 4 h rainfall events division method was established.Based on the relatively long time series of rainfall and water quality observation data spanning more than one year,the characteristics of rainfall and water quality changes and the variation of water quality indicators under different rainfall events were analyzed.SPSS correlation analysis method was used to analyze the correlation between rainfall events and typical water quality indicators.The results showed that the rainfall in Tanshui River Basin was extremely uneven in time distribution,the water quality was sensitive to rainfall intensity.The responses of different water quality indicators to rainfall events was significantly different,the dissolved oxygen concentration in all rainfall events was lower than that in sunny days,and the effect of torrential rain on dissolved oxygen reduction was greater.Turbidity and conductivity showed obvious positive and negative growth with rainfall event intensity,indicated that the sediments response to rainfall-runoff events was rapid and obvious.The variation tendency of pollution indexes such as permanganate index,ammonia nitrogen,total phosphorus and total nitrogen was similiar,with the increase of rainfall intensity,the water quality indexes increased first and then decreased,and the increase range was the largest during torrential rain.The reduction and treatment of oxygen-consuming pollutants in torrential rain deserved more attention for the improvement of dissolved oxygen,while the permanganate index,ammonia nitrogen,total phosphorus,total nitrogen should promote the coordinated treatment and synchronous reduction of non-point source pollution in flood seasons.Considering that different rainfall events had different effects on different pollution indexes,the fine response of pollution peak clipping could be carried out according to the characteristics of key pollution indexes and weather forecast.